Materials Science

Fine Lines in Glass

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Science  28 Apr 2006:
Vol. 312, Issue 5773, pp. 500
DOI: 10.1126/science.312.5773.500b

The feature resolution attainable using photolithography has generally been limited by the wavelength of the incident light. However, as light sources approach the extreme ultraviolet (EUV), the polymer resists become the limiting factor because etching leaves behind rough edges, probably due to polydispersity. A promising alternative is to fabricate resists from amorphous films composed of small organic molecules with high glass-transition temperatures. In this vein, Chang et al. prepared films with glass transitions at ∼120°C from derivatives of C-4-hydroxyphenyl-calix[4]resorcinarenes. A fluorinated photoacid was incorporated to solubilize local calixarenes on exposure to light, resulting in a positive-tone resist. The authors optimized the material by varying the extent of calixarene hydroxyl protection with bulky tert-butyloxycarbonyl (t-Boc) groups. At 70% t-Boc incorporation, EUV irradiation produced lines with 30 nm resolution. Moreover, a line-edge roughness below 5 nm was obtained for 50-nm lines. — PDS

J. Mater. Chem. 16, 1470 (2006).

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